This invention relates to a process for the machine washing and cleaning of solid materials, in particular textiles, and to an apparatus for carrying out this process.
A washing and cleaning process has been disclosed in German Published Application (Auslegeschrift) No. 2,543,946, corresponding to United States patent application Ser. No. 618,461, filed Oct. 1, 1975, now abandoned in favor of its continuation Ser. No. 872,561, filed Jan. 26, 1978, in which the wash liquor, which can contain a water-soluble sequestrant and customary surface-active compounds, is continuously or intermittently removed during the cleaning process from the container in which the cleaning process takes place, and is passed through a filter bed which is charged with a water-insoluble cation-exchanging, bound-water containing alumino silicate having a calcium binding power of at least 50 mg CaO/gm, for example, one corresponding to the following formula: EQU (Na.sub.2 O.sub.x.Al.sub.2 O.sub.3.(SiO.sub.2).sub.y
in which:
x=0.7 to 1.5, and PA1 y=1.3 to 3.3.
After passing through the filter bed, which must be designed to retain the aluminosilicate, the wash liquor returns to the cleaning vessel or substrate. The water-soluble sequestrant contained in the wash liquor is regenerated by the contact with the cation-exchanger. The cleaning effect which can thereby be achieved may surpass that of a conventional cleaning or washing process in which the aluminosilicate is suspended in the detergent liquor and is in direct contact with the substrate to be cleaned. However, problems may arise due to blockage of the filter, which is particularly likely to occur if very finely divided and highly reactive aluminosilicate is used or if large quantities of dirt and lint from textiles, or food residues in the case of dishwashing, are present as an added load on the filter. Although suitable design of the filter or the provision of devices for reversing the direction of flow to free the blocked filter surface, can provide substantial improvements, the problem remains.